Methods of frictional coupling

Abstract

A method of forming a coupling between a first part and a second part is disclosed. The method includes providing a first surface of the first part. The first surface has a first shape and a surface roughness average that is less than or equal to about 500 microinches (13 microns). The method also includes forming a second surface of the second part where the second surface has a second shape and the first shape and the second shape are substantially complementary shapes. Projections form at least a portion of the second surface in a preselected pattern, and are configured to produce a friction fit between the first surface and the second surface when the first surface and the second surface are biased against each other. The projections have an average elastic compressive range substantially equal to the surface roughness average.

What is claimed is: 
     
       1. A method of forming a coupling between a first part and a second part, the method comprising:
 providing a first surface of the first part,
 wherein the first surface has a first shape and a surface roughness average that is less than or equal to about 500 microinches (13 microns); 
 
 forming a second surface of the second part, wherein:
 the second surface has a second shape, 
 the first shape and the second shape are substantially complementary shapes, 
 projections, forming at least a portion of the second surface, are arranged in a preselected pattern and are configured to produce an anisotropic friction fit, along an axis, between the first part and the second part when the first part and the second part are biased against each other with a predetermined force, 
 the projections have an average elastic compressive range substantially equal to the surface roughness average, and 
 the average elastic compressive range is defined by limits of elastic deformation of the projections; and 
 
 biasing the first part and the second part against each other with a predetermined force to create the anisotropic friction fit, along the axis, between the first part and the second part. 
 
     
     
       2. The method of  claim 1 , wherein the predetermined force is selected such that the elastic deformation of the projections reaches the average elastic compressive range. 
     
     
       3. The method of  claim 1 , wherein the predetermined force is greater than zero and causes the elastic deformation of the projections that does not exceed the average elastic compressive range. 
     
     
       4. The method of  claim 1 , wherein biasing the first part and the second part against each other includes forming one of a press fit and a shrink fit between the first part and the second part. 
     
     
       5. The method of  claim 1 , wherein:
 each of the projections comprises a first portion and a second portion, 
 the first portion extends in a direction, oblique to the first surface, and 
 the second portion extends obliquely from the first portion. 
 
     
     
       6. The method of  claim 5 , wherein:
 the first portion forms an undercut surface on each of the projections, and 
 the undercut surface is maintained as the first surface and second surface are biased against each other. 
 
     
     
       7. The method of  claim 1 , wherein:
 each of the projections comprises a first portion, a second portion, and a third portion, 
 the first portion defines an arcuate profile, 
 the second portion extends from the first portion, 
 the third portion extends from the second portion, and 
 the second portion and the third portion are both substantially linear. 
 
     
     
       8. The method of  claim 7 , wherein the third portion defines a third surface that is angled relative to the second surface. 
     
     
       9. A method of at least partially forming a second part for a coupling between a first part and the second part, the first part including a first surface having a first shape and a surface roughness average that is less than or equal to about 500 microinches (13 microns), the method comprising:
 forming a second surface of the second part, wherein:
 the second surface has a second shape, 
 the first shape and the second shape are substantially complementary shapes, 
 projections, forming at least a portion of the second surface, are arranged in a preselected pattern and are configured to produce an anisotropic friction fit, along an axis, between the first part and the second part when the first part and the second part are biased against each other with a predetermined force, 
 the projections have an average elastic compressive range substantially equal to the surface roughness average, 
 the average elastic compressive range is defined by limits of elastic deformation of the projections. 
 
 
     
     
       10. A method of forming a second surface of a second part for coupling with a first surface of a first part, the first surface having a first shape and a surface roughness average that is less than or equal to about 500 microinches (13 microns), the method comprising:
 forming the second surface having a second shape, wherein:
 the first shape and the second shape are substantially complementary shapes, 
 projections, forming at least a portion of the second surface, are arranged in a preselected pattern and are configured to produce an anisotropic friction fit between the first part and the second part when the first part and the second part are biased against each other with a predetermined force, 
 the projections have an average elastic compressive range substantially equal to the surface roughness average, and 
 the average elastic compressive range is defined by limits of elastic deformation of the projections. 
 
 
     
     
       11. The method of  claim 10 , wherein:
 each of the projections comprises a first portion and a second portion, 
 the first portion extends in a direction, oblique to the first surface, and 
 the second portion extends obliquely from the first portion. 
 
     
     
       12. The method of  claim 11 , wherein:
 the first portion forms an undercut surface on each of the projections, and 
 the undercut surface is maintained as the first surface and second surface are biased against each other. 
 
     
     
       13. The method of  claim 10 , wherein:
 each of the projections comprises a first portion, a second portion, and a third portion, 
 the first portion defines an arcuate profile, 
 the second portion extends from the first portion, 
 the third portion extends from the second portion, and 
 the second portion and the third portion are both substantially linear. 
 
     
     
       14. The method of  claim 13 , wherein the third portion defines a third surface that is angled relative to the second surface. 
     
     
       15. A method of forming a coupling between a first surface of a first part and a second surface of a second part, the method comprising:
 providing the first surface, having a first shape and a surface roughness average that is less than or equal to about 500 microinches (13 microns); 
 forming the second surface, having a second shape, wherein
 the first shape and the second shape are substantially complementary shapes, and 
 projections, forming at least a portion of the second surface are arranged in a preselected pattern and configured to produce an anisotropic friction fit along an axis, between the first part and the second part when the first part and the second part are biased against each other, 
 the projections have an average elastic compressive range that is substantially equal to the surface roughness average, and 
 the average elastic compressive range is defined by limits of elastic deformation of the projections; and 
 
 biasing the first part and the second part against each other with a predetermined force to create the anisotropic friction fit, along the axis, between the first part and the second part. 
 
     
     
       16. The method of  claim 15 , wherein the predetermined force is sufficient to reach the average elastic compressive range. 
     
     
       17. The method of  claim 15 , wherein the predetermined force is greater than zero, but is insufficient to exceed the average elastic compressive range. 
     
     
       18. The method of  claim 15 , wherein the preselected pattern is formed by one of lithographically applied photoresist, chemical machining, and laser etching. 
     
     
       19. The method of  claim 15 , wherein forming the second surface comprises forming the second surface on one of a shank and a receiver. 
     
     
       20. The method of  claim 15 , wherein:
 each of the projections comprises a first portion and a second portion, 
 the first portion extends in a direction, oblique to the first surface, and 
 the second portion extends obliquely from the first portion.